This invention relates generally to stents employed to maintain in an open configuration a body lumen such as a duct or vessel, and in particular to a stent having a hollow and inflatable wall.
The employment of stents to maintain otherwise closed or occluded body lumens such as ducts or vessels, for example, in an open configuration is a well-recognized treatment procedure. Current commonly used stents include self-expanding stents as described in U.S. Pat. No. 4,655,771, for example, and stents which are expanded at the lumen site by a balloon which is inflated within the stent. In either case, the stents are usually constructed of metal, and therefore generally possess a degree of stiffness and a minimal pliability.
It is therefore a primary object of the present invention to provide a stent having a wall which is soft and pliable upon insertion, but which has the capability to provide the proper magnitude of stiffness and rigidity after placement at the site of treatment. Another object of the present invention is to provide such a stent wherein at least a portion of its wall structure is a hollow and inflatable wall fabricated of a semi-permeable membrane. Yet another object of the present invention is to provide such a stent wherein the hollow wall has disposed therein a hydrophilic material capable of absorbing a liquid to thereby increase the volume of the material and consequently inflate the wall. Still another object of the present invention is to provide such a stent wherein the hydrophilic material has therewith a drug. These and other objects of the invention will become apparent throughout the following description.